1/*
2 * Copyright (C) 2012, 2014 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef JITStubRoutine_h
27#define JITStubRoutine_h
28
29#if ENABLE(JIT)
30
31#include "ExecutableAllocator.h"
32#include "MacroAssemblerCodeRef.h"
33#include <wtf/RefCounted.h>
34#include <wtf/Vector.h>
35
36namespace JSC {
37
38class JITStubRoutineSet;
39class RepatchBuffer;
40
41// This is a base-class for JIT stub routines, and also the class you want
42// to instantiate directly if you have a routine that does not need any
43// help from the GC. If in doubt, use one of the other stub routines. But
44// if you know for sure that the stub routine cannot be on the stack while
45// someone triggers a stub routine reset, then using this will speed up
46// memory reclamation. One case where a stub routine satisfies this
47// condition is if it doesn't make any calls, to either C++ or JS code. In
48// such a routine you know that it cannot be on the stack when anything
49// interesting happens.
50// See GCAwareJITStubRoutine.h for the other stub routines.
51class JITStubRoutine {
52    WTF_MAKE_NONCOPYABLE(JITStubRoutine);
53    WTF_MAKE_FAST_ALLOCATED;
54public:
55    JITStubRoutine(const MacroAssemblerCodeRef& code)
56        : m_code(code)
57        , m_refCount(1)
58    {
59    }
60
61    // Use this if you want to pass a CodePtr to someone who insists on taking
62    // a RefPtr<JITStubRoutine>.
63    static PassRefPtr<JITStubRoutine> createSelfManagedRoutine(
64        MacroAssemblerCodePtr rawCodePointer)
65    {
66        return adoptRef(new JITStubRoutine(MacroAssemblerCodeRef::createSelfManagedCodeRef(rawCodePointer)));
67    }
68
69    virtual ~JITStubRoutine();
70
71    // MacroAssemblerCodeRef is copyable, but at the cost of reference
72    // counting churn. Returning a reference is a good way of reducing
73    // the churn.
74    const MacroAssemblerCodeRef& code() const { return m_code; }
75
76    static MacroAssemblerCodePtr asCodePtr(PassRefPtr<JITStubRoutine> stubRoutine)
77    {
78        if (!stubRoutine)
79            return MacroAssemblerCodePtr();
80
81        MacroAssemblerCodePtr result = stubRoutine->code().code();
82        ASSERT(!!result);
83        return result;
84    }
85
86    void ref()
87    {
88        m_refCount++;
89    }
90
91    void deref()
92    {
93        if (--m_refCount)
94            return;
95        observeZeroRefCount();
96    }
97
98    // Helpers for the GC to determine how to deal with marking JIT stub
99    // routines.
100    uintptr_t startAddress() const { return m_code.executableMemory()->startAsInteger(); }
101    uintptr_t endAddress() const { return m_code.executableMemory()->endAsInteger(); }
102    static uintptr_t addressStep() { return jitAllocationGranule; }
103
104    static bool canPerformRangeFilter()
105    {
106#if ENABLE(EXECUTABLE_ALLOCATOR_FIXED)
107        return true;
108#else
109        return false;
110#endif
111    }
112    static uintptr_t filteringStartAddress()
113    {
114#if ENABLE(EXECUTABLE_ALLOCATOR_FIXED)
115        return startOfFixedExecutableMemoryPool;
116#else
117        UNREACHABLE_FOR_PLATFORM();
118        return 0;
119#endif
120    }
121    static size_t filteringExtentSize()
122    {
123#if ENABLE(EXECUTABLE_ALLOCATOR_FIXED)
124        return fixedExecutableMemoryPoolSize;
125#else
126        UNREACHABLE_FOR_PLATFORM();
127        return 0;
128#endif
129    }
130    static bool passesFilter(uintptr_t address)
131    {
132        if (!canPerformRangeFilter()) {
133            // Just check that the address doesn't use any special values that would make
134            // our hashtables upset.
135            return address >= jitAllocationGranule && address != std::numeric_limits<uintptr_t>::max();
136        }
137
138        if (address - filteringStartAddress() >= filteringExtentSize())
139            return false;
140
141        return true;
142    }
143
144    virtual bool visitWeak(RepatchBuffer&);
145
146protected:
147    virtual void observeZeroRefCount();
148
149    MacroAssemblerCodeRef m_code;
150    unsigned m_refCount;
151};
152
153// Helper for the creation of simple stub routines that need no help from the GC.
154#define FINALIZE_CODE_FOR_STUB(codeBlock, patchBuffer, dataLogFArguments) \
155    (adoptRef(new JITStubRoutine(FINALIZE_CODE_FOR((codeBlock), (patchBuffer), dataLogFArguments))))
156
157} // namespace JSC
158
159#endif // ENABLE(JIT)
160
161#endif // JITStubRoutine_h
162
163